Nicola Sturgeon has been accused of misleading Scots about a secret deal she signed involving a Chinese company accused of corruption and the involvement of a major SNP donor.

Opposition parties highlighted disclosures in 70 pages of documents released under the Freedom of Information Act as evidence that the agreement with a consortium of two firms included specific projects, including a factory to build thousands of prefabricated homes.

The parties also questioned the involvement of Sir Brian Souter, the Stagecoach tycoon, who said at the time he had “nothing to do” with the deal despite passing on the Scottish Government’s contact details to one of the firms.

Another of documents published by the Scottish Government suggested he was “likely to be one of many co-investors.” However, SNP ministers vehemently denied any wrongdoing and Sir Brian said he held “exploratory discussions” but “the investment opportunities were not aligned to our criteria.”

The Scottish Government did not publicise the memorandum of understanding with the consortium when Ms Sturgeon signed it in March and the deal only became public in the UK the following month when it was spotted on SinoFortone’s website.

The documents published under FOI included an email dated March 7 this year stated that the consortium wanted to build a factory in the central belt to produce between 3,000 and 5,000 prefabricated homes.

A briefing note for the First Minister ahead of the secret signing on March 21 in her Bute House official residence said the deal would bring “significant Chinese investment into Scotland in areas such as clean energy, transport and affordable housing.”

Another email to Ms Sturgeon, dated April 2, said Sir Brian was “likely to be one of many co-investors and his involvement is not surprising given the scale of his commitment to Scotland as one of our top businessmen.”

On the same day, in response to media queries, officials agreed to issue a statement saying Sir Brian “had not involvement in the Memorandum of Understanding, was not at the meeting and did not sign it.”

The documents also included a draft press release for the day of the signing, which was never released. Jackie Baillie, Scottish Labour’s jobs spokesman, said ministers should make an urgent parliamentary statement and Holyrood’s economy committee must investigate the deal.

She said: “The SNP have misled people on Brian Souter's involvement in this deal. We were told that SNP donor Brian Souter had no involvement in this deal, yet these papers expose the fact that Scottish Government officials have been working with Mr Souter on this for months.”

Keith Brown, the Cabinet Minister for the Economy, said the papers confirmed that discussions were at an early stage and no specific projects had been agreed.

He said: “These papers show how misguided opposition politicians have been over this issue, and expose their assertions as unfounded. It is clear that while all potential investment has to be considered carefully, opposition parties should be wary about deterring potential investment.”

A spokesman for Sir Brian said: “Souter Investments had exploratory discussions with SinoFortone and a number of other parties regarding investing together in Scotland. However, as made clear to the company and the Scottish Government, the investment opportunities were not aligned to our criteria.”